Facebook founder and CEO Mark Zuckerberg looks on during a news conference at Facebook headquarters on October 6, 2010 in Palo Alto, California. Zuckerberg announced the addition of a revamped personal groups feature and the ability to download everything you have posted to Facebook. (Photo by Justin Sullivan/Getty Images)

By
Cox Media Group National Content Desk

A Senate committee launched an inquiry Tuesday into Facebook after allegations surfaced that the social media company suppressed conservative news topics in its highly visible trending news section.

In a letter to Facebook Chairman and CEO Mark Zuckerberg, Republican Sen. John Thune, chairman of the Senate Committee on Commerce, Science and Transportation, asked for Facebook staff to brief the committee on how the site moderates its "Trending Topics" section.

Thune also asked the company whether "news curators in fact manipulated the content of the Trending Topics section, either by targeting news stories related to conservative views for exclusion or by injecting non-trending content."

"If true, these allegations compromise Facebook's 'open culture' and mission 'to make the world more open and connected,'" Thune wrote.

The inquiry was launched a day after Gizmodo reported Facebook had a tendency to downplay conservative news, even when such topics were trending organically on the site, citing unnamed former Facebook news curators. Employees also sometimes put stories into the site's Trending Topics section when they were not trending to give issues that they deemed important higher visibility, according to the report.

"Facebook has enormous influence on users' perceptions of current events, including political perspectives," Thune wrote. "If Facebook presents its Trending Topics section as the result of a neutral, objective algorithm, but it is in face subjective and filtered to support or suppress particular political viewpoints, Facebook's assertion that it maintains a 'platform for people and perspectives from across the political spectrum' misleads the public."

It was not clear whether the alleged manipulation was still going on, as the curators quoted by Gizmodo had left Facebook.

Facebook acknowledged Tuesday that it had received Thune's letter. In a statement, the company said it "look(ed) forward to addressing his questions."

First Amendment lawyer Floyd Abrams told The New York Times that Facebook could comply with the request or refuse on First Amendment grounds.

"The notion of Congress looking into or investigating how a medium of communication decides what to say threatens on its face First Amendment rights," Abrams told the newspaper.

Harvey Silvergate, another First Amendment attorney, told the Boston Herald that Facebook's purported moderation was likely legal, though ethically questionable. It could be argued that, as a major distributor of information, Facebook could be "compared to telephone companies that are bound to neutrally relay communications," the Herald reported.

Thune's request for answers from Facebook appeared to mark a shift in position for the South Dakota senator. In 2007, he spoke out against a Federal Communications Commission rule that required broadcasters to provide equal air time to all sides while discussing controversial issues, calling it "Orwellian."

"I know the hair stands up on the back of my neck when I hear government officials offering to regulate the news media and talk radio to ensure fairness," Thune said.